Presently, many earth moving machines such as buckets, loaders, scrapers, and bulldozers are fitted with cutting edges and with teeth which project forwardly of the cutting edges. The teeth tend to break up the earth or other working medium to increase penetration of the cutting edges as well as to increase the overall efficiency of the machine. Replaceable cutting edges and teeth are essential inasmuch as the main earth working surface, i.e. the bucket bottom, the scraper blade, etc., is usually far too costly to subject to localized wear.
The earth working surfaces of such machines are usually protected by such cutting edge and tooth assemblies in areas which are in almost constant contact with earth, rock, sand and other abrasive materials. Because of this, the useful life of these individual components is relatively short. To improve the useful life of such working components, especially cutting edges, various innovations have been employed.
Heavier metal sections have been utilized for the individual cutting edge and stronger materials such as alloy steel as well as hardening heat treatments for the cutting edge surfaces have been employed with varying results.
Tooth assemblies, which are most advantageously utilized to form a leading edge for the cutting edges in extremely hard and relatively impenetrable working mediums, have also extended the wear life of the associated cutting edges inasmuch as they act as a shield for such cutting edges.
There have been numerous prior art attempts to provide replaceable cutting edges and replaceable tooth members for earth working surfaces. Some attempts have involved the use of bolt-on adapters for securing teeth to the cutting edge elements. Since earth working teeth are often very heavily loaded, such bolts were subject to breakage under shear forces and the tooth adapters often broke under the stresses applied. To overcome this problem, integral teeth and cutting edge modules were introduced. Examples of such innovations are found in U.S. Pat. No. 3,059,357 to Irish and U.S. Pat. No. 3,653,133 to Black et al., of common assignment herewith. Such one-piece cutting edge and tooth designs effectively eliminated premature bolt and adapter breakage but introduced a new problem.
In such integral cutting edge and tooth assemblies, tooth wear is much more rapid than cutting edge wear. Once the tooth is worn away, the cutting edge is no longer capable of providing good penetration in hard surface working mediums. In order to provide the machine with a new tooth element, the relatively unworn integral cutting edge portion must be discarded. This obvious waste of material is inefficient and highly disadvantageous economically.
Other prior art attempts to provide various replaceable components for earth working surfaces are found in U.S. Pat. Nos. 2,113,420, 2,385,395, 2,393,706, 2,798,403, 2,874,491, 2,925,673, 3,440,745 to Younie, Baer, Page, Launder, Larsen, Sennholtz, and Palm respectively.